It's already possible to run xorg non-root with nouveau. Intel is a problem last time I tried (about a month ago).
I use sgid and sudo to make xorg run as nobody:video. This does require marking /dev/input/* as owned by :video. Furthermore, you need to disable MIT-SHM for QT apps to work. Finally, VT-switching does not work and keyboard input is dumped into the terminal (huge privacy issue). But it works.
How does this make things better?